Volume 16,Issue 1,2018 Table of Contents
2018, 16(1):1-7.
Abstract:
Tar geting the problems of water security and water cycle under changing environments, this paperintr oduces the basic concepts, theories, and implications of water system. From the inter disciplinary perspective, the frontier of water science deveopment will be combining natura lscience and social science so as to study the water problem under changing environments. This paper analyzes the develo pment trend of the study on nexus of hydroso cialecology. It emphasizes the importance of studies on the coupling and decoupling of water system, the sensitivity of water syst emmodeling , and the monitoring of water system. It also discusses the necessity of the coevolution and ensemble response mechanism between naturalsy stem and human system to the construction of water system coupling models. Taking Huai River basin, Poyang Lake, and Han River basin as examples, this paper illustrates the practical and guiding significance of water system theory in China from different perspectives. The further study of water system theory should streng then the internal mechanism and generalization accuracy in order to enhance the adapt ability of water system models to climate and environmental changes. The communication between water manaement decisio nmakers and researchers also should be propelled.
Tar geting the problems of water security and water cycle under changing environments, this paperintr oduces the basic concepts, theories, and implications of water system. From the inter disciplinary perspective, the frontier of water science deveopment will be combining natura lscience and social science so as to study the water problem under changing environments. This paper analyzes the develo pment trend of the study on nexus of hydroso cialecology. It emphasizes the importance of studies on the coupling and decoupling of water system, the sensitivity of water syst emmodeling , and the monitoring of water system. It also discusses the necessity of the coevolution and ensemble response mechanism between naturalsy stem and human system to the construction of water system coupling models. Taking Huai River basin, Poyang Lake, and Han River basin as examples, this paper illustrates the practical and guiding significance of water system theory in China from different perspectives. The further study of water system theory should streng then the internal mechanism and generalization accuracy in order to enhance the adapt ability of water system models to climate and environmental changes. The communication between water manaement decisio nmakers and researchers also should be propelled.
2018, 16(1):8-13.
Abstract:
In a water diversion project, if the water level before the pump is too low, the security of the pumping station will be endangered; if the water level is too high, the safety of the surrounding area will be endangered. So, it is particularly important to study the change of water level in the reservoir. The paper, based on the Nansi Lake section of the eastern route of the South to North Water Transfer Project in Shandong Province, explores the water level variation pattern before the pump under different conditions of initial water level, inflow and outflow, and opening time differ ence between pumping stations. Firstly, we used the coupled model to numerically simulate different diversion plans. Then we selected 23 water diversion plans and their beforepump water level obtained from numerical simulation as samples to train the BP neural network. Thus, we established a prediction model for water level regulation and had it veri fied. Finally we predicted the water level before the pump in different diversion plans using the model. The results showed that the BP neural network model has a strong predictive power. Its results were basically consistent with the results of the coupled model, with the relative error of water depth less than 9. 15% . Meanw hile the modelcs calculation efficiency improved by 96. 67% .
In a water diversion project, if the water level before the pump is too low, the security of the pumping station will be endangered; if the water level is too high, the safety of the surrounding area will be endangered. So, it is particularly important to study the change of water level in the reservoir. The paper, based on the Nansi Lake section of the eastern route of the South to North Water Transfer Project in Shandong Province, explores the water level variation pattern before the pump under different conditions of initial water level, inflow and outflow, and opening time differ ence between pumping stations. Firstly, we used the coupled model to numerically simulate different diversion plans. Then we selected 23 water diversion plans and their beforepump water level obtained from numerical simulation as samples to train the BP neural network. Thus, we established a prediction model for water level regulation and had it veri fied. Finally we predicted the water level before the pump in different diversion plans using the model. The results showed that the BP neural network model has a strong predictive power. Its results were basically consistent with the results of the coupled model, with the relative error of water depth less than 9. 15% . Meanw hile the modelcs calculation efficiency improved by 96. 67% .
2018, 16(1):14-21.
Abstract:
Copula is an important tool for structuring the multivariat ejoint distribution and analyzing the correlation structur ebetween random variables. This paper reviews the research and application of Copula in drought since 2005 and discusses the current problems of Copula method and the development direction of Copula theory. Firstly, the parameter estimation of high-dimensional Copula function is not accur ateenough. Although the high-dimensional Copula const ruction methods such as nested method, hybrid method, and conditionhy brid method can essentially simplify parameter estimation, and the Copula parameter estimation method based on Bayesian theory is a significant improvement over the traditional method, still they cannot deliver satisfacto rycomputat ionamount, confidence level, and sample size at the same time. The parameter estimation method of high-dimensional Copula theory is still a difficult pointin the research of Copula theory. Secondly , the characteristics of drought are sensitive to time; thus, the Copula function needs to be time-varying in order to be applied to drought problems. The Copula theory with temporal and spatial variation can beused to analyze drought. It is one of the futur edir ections of Copula research. Thirdly, Copula method can be applied in a number of directions, and also need to be further combined with ot her frameworks.
Copula is an important tool for structuring the multivariat ejoint distribution and analyzing the correlation structur ebetween random variables. This paper reviews the research and application of Copula in drought since 2005 and discusses the current problems of Copula method and the development direction of Copula theory. Firstly, the parameter estimation of high-dimensional Copula function is not accur ateenough. Although the high-dimensional Copula const ruction methods such as nested method, hybrid method, and conditionhy brid method can essentially simplify parameter estimation, and the Copula parameter estimation method based on Bayesian theory is a significant improvement over the traditional method, still they cannot deliver satisfacto rycomputat ionamount, confidence level, and sample size at the same time. The parameter estimation method of high-dimensional Copula theory is still a difficult pointin the research of Copula theory. Secondly , the characteristics of drought are sensitive to time; thus, the Copula function needs to be time-varying in order to be applied to drought problems. The Copula theory with temporal and spatial variation can beused to analyze drought. It is one of the futur edir ections of Copula research. Thirdly, Copula method can be applied in a number of directions, and also need to be further combined with ot her frameworks.
2018, 16(1):22-27.
Abstract:
The rainfall-runoff relat ionship in Sanchuan watershed has changed significantly due to the climate change and intensive human activities. The variation of rainfall-runoff relationship threatens the urban water supply and spring protection work in Jinan city. In this paper, we investigated the variationpat terns and analyzed the internal mechanism and driving factors that caused the variation of rainfall-runoff relationship in the past fifty years ( 1964-2011) . The Mann-Kendall test , cumulative anomraly, and sliding partial correlation coefficient methods were used for characteristics analysis. The analysis results indicated that the rainfall increased significantly due to the climate change. However, the runoff decreased insignificantly in the pastfifty years due to human activities such as soil and water conservation and water consumption for social and economic purposes. The change-point of rainfall-runoff relationship occurred in 1988. The annual rainfall in 1988-2011 increased by 12. 57% and the annual runoff decreased by 8. 85% as compared to those prior to the change-point ( in 1964-1987) . The human activities including water storage and supply projects and soil and water conservation practices were the mainfactors impacting the rainfall-runoff relationship in Sanchuan watershed. The analysis demonstrated that the climate change and human activities had opposite effects on the rainfall-runoff relationship in Sanchuan watershed.
The rainfall-runoff relat ionship in Sanchuan watershed has changed significantly due to the climate change and intensive human activities. The variation of rainfall-runoff relationship threatens the urban water supply and spring protection work in Jinan city. In this paper, we investigated the variationpat terns and analyzed the internal mechanism and driving factors that caused the variation of rainfall-runoff relationship in the past fifty years ( 1964-2011) . The Mann-Kendall test , cumulative anomraly, and sliding partial correlation coefficient methods were used for characteristics analysis. The analysis results indicated that the rainfall increased significantly due to the climate change. However, the runoff decreased insignificantly in the pastfifty years due to human activities such as soil and water conservation and water consumption for social and economic purposes. The change-point of rainfall-runoff relationship occurred in 1988. The annual rainfall in 1988-2011 increased by 12. 57% and the annual runoff decreased by 8. 85% as compared to those prior to the change-point ( in 1964-1987) . The human activities including water storage and supply projects and soil and water conservation practices were the mainfactors impacting the rainfall-runoff relationship in Sanchuan watershed. The analysis demonstrated that the climate change and human activities had opposite effects on the rainfall-runoff relationship in Sanchuan watershed.
2018, 16(1):28-34.
Abstract:
In order to understand the actual evapotranspiration ( ETa ) process in cold wetland and to make effective management of water resources, we analyzed the variation of ETa in Harbin Jinhewan wetland and its influencing factors under different time scales based on the measured dat a of eddy covariance system from August 2015 to July 2016. The annual ETa was 660mm during the study period, and the maximum daily ETa was up to 8. 1mm/ d. The ETa was the highest in summer ( 3.4 mm/ d) , second highest in spring ( 2.3 mm/ d) and autumn ( 1.4 mm/ d) , and was the lowest and stable in winter ( 0.1 mm/ d) . The crop coefficient(Kc) increased from 0.95 to about 1.18 in May ( plantg rowing period) .The Kc was between 1.05-1. 18 from June to the middle of August (plant stabilizing period), and it decreased from 1.05 to 0.85 during late August to September (plant withering period) . The main meteorological factors affecting the ETa were net radiation and vapor pressure deficit. The correlations between ETa and meteorological factors were different at differenttime scales. The correlations of net radiation and water vaporpr essure deficit with ETa were significant at both scales, but net radiation was more correlated to ETa at the 30min scale. The correlation between temperature and ETa was basically consistent at both scales. High temperature would promote ETa and low temperature would suppress ETa. At the daily scale, the correlation between air humidity and ETa was obvious in autumn and winter; at the 30 min scale, the correlation was o bvious in spring and winter. The correlation between wind speed and ETa was only obvio us in summer and autumn at the 30 min scale.
In order to understand the actual evapotranspiration ( ETa ) process in cold wetland and to make effective management of water resources, we analyzed the variation of ETa in Harbin Jinhewan wetland and its influencing factors under different time scales based on the measured dat a of eddy covariance system from August 2015 to July 2016. The annual ETa was 660mm during the study period, and the maximum daily ETa was up to 8. 1mm/ d. The ETa was the highest in summer ( 3.4 mm/ d) , second highest in spring ( 2.3 mm/ d) and autumn ( 1.4 mm/ d) , and was the lowest and stable in winter ( 0.1 mm/ d) . The crop coefficient(Kc) increased from 0.95 to about 1.18 in May ( plantg rowing period) .The Kc was between 1.05-1. 18 from June to the middle of August (plant stabilizing period), and it decreased from 1.05 to 0.85 during late August to September (plant withering period) . The main meteorological factors affecting the ETa were net radiation and vapor pressure deficit. The correlations between ETa and meteorological factors were different at differenttime scales. The correlations of net radiation and water vaporpr essure deficit with ETa were significant at both scales, but net radiation was more correlated to ETa at the 30min scale. The correlation between temperature and ETa was basically consistent at both scales. High temperature would promote ETa and low temperature would suppress ETa. At the daily scale, the correlation between air humidity and ETa was obvious in autumn and winter; at the 30 min scale, the correlation was o bvious in spring and winter. The correlation between wind speed and ETa was only obvio us in summer and autumn at the 30 min scale.
6 Multi-objective optimization of an improved Xin'anjiang model: A case study in Linhuanji catchment
2018, 16(1):35-41.
Abstract:
In plain irrigatio n areas, human exploitation and irrigation have a great impact on local hydrological processes, and material and energy exchange frequently between surface flow and groundwater. In these areas, single-objective calibration methods cannot effectively simulate river discharge and groundwater depth at the same time. Therefore, we established a surface-groundwater coupling model based on Xin'anjiang model combined with a groundwater reservoir, and we built a multi-objective function containing discharge and groundw- ater data. Then we used SCE-UA to calibrate the sensitive parameters selected by MCAT and we compared the results of single-objec- tive and multi-objective calibration. Results showed that the multi-objective calibration method used in this study worked more efficiently than many former ones. It can effectively and accurately simulate discharge and water level simultaneously. The coupling model does well in simulating the hydrological processes in Linhuanji catchment. It can provide reference for surface-groundwater dynamic simulation and water resources assessment in plain irrigation areas.
In plain irrigatio n areas, human exploitation and irrigation have a great impact on local hydrological processes, and material and energy exchange frequently between surface flow and groundwater. In these areas, single-objective calibration methods cannot effectively simulate river discharge and groundwater depth at the same time. Therefore, we established a surface-groundwater coupling model based on Xin'anjiang model combined with a groundwater reservoir, and we built a multi-objective function containing discharge and groundw- ater data. Then we used SCE-UA to calibrate the sensitive parameters selected by MCAT and we compared the results of single-objec- tive and multi-objective calibration. Results showed that the multi-objective calibration method used in this study worked more efficiently than many former ones. It can effectively and accurately simulate discharge and water level simultaneously. The coupling model does well in simulating the hydrological processes in Linhuanji catchment. It can provide reference for surface-groundwater dynamic simulation and water resources assessment in plain irrigation areas.
2018, 16(1):42-49.
Abstract:
In order to quantitatively evaluate the over all status and the development trend of the water resources carrying capacity in Anhui Province and diagnose the key indexes which made the system vulnerable, we used connection number method to establish an evaluation model for the water resources carrying capacity of Anhui Province, and used the set pair subtractive situation to identify vulnerable indexes. In this study we proposed a new resear chidea. First, we evaluated the over all status of the water resources carrying capacity . Second, we identified vulnerable indexes based on the evaluation results. Then we regulated the vulnerable indexes. At last, we re-evaluated the water resources carrying capacity . The results showed that the comprehensive evaluation grade of water resources carrying capacity in Anhui Province from 2005 to 2015 was near Grade 2 overload. Despite the tendency of slow improvement, the carrying capacity was not satisfactory. After the vulnerable indexes were regulated, the evaluation results improved significantly . The evaluation and diagnostic methods and research ideas used in this paper can provide technical support for the rational allocation and regulation of water resources in Anhui Province.
In order to quantitatively evaluate the over all status and the development trend of the water resources carrying capacity in Anhui Province and diagnose the key indexes which made the system vulnerable, we used connection number method to establish an evaluation model for the water resources carrying capacity of Anhui Province, and used the set pair subtractive situation to identify vulnerable indexes. In this study we proposed a new resear chidea. First, we evaluated the over all status of the water resources carrying capacity . Second, we identified vulnerable indexes based on the evaluation results. Then we regulated the vulnerable indexes. At last, we re-evaluated the water resources carrying capacity . The results showed that the comprehensive evaluation grade of water resources carrying capacity in Anhui Province from 2005 to 2015 was near Grade 2 overload. Despite the tendency of slow improvement, the carrying capacity was not satisfactory. After the vulnerable indexes were regulated, the evaluation results improved significantly . The evaluation and diagnostic methods and research ideas used in this paper can provide technical support for the rational allocation and regulation of water resources in Anhui Province.
2018, 16(1):50-56.
Abstract:
The medium and small riv ers in China generally have low flood contro lstandards and urgent lyneed st rengthened flood forecasting , especially in high-cold mountaino us areas with insufficient stations and data, where it is difficult to disting uish the runoff produced by snowmelt from that by precipitation, which enhances the difficulty of flood for ecasting . Snowmelt Runoff Model ( SRM ) is a hydro logical model fo rsimulating and forecasting the snow melt runoff in mountainous watersheds. It plays an important role in the study of mountainous watersheds with snow melt and precipitation as the main runoff sources. Based on SRM and taking Kuitun River as a typical case of medium and small rivers in high-cold mountainous areas of Xinjiang , we simulated the daily runoff of the catchment by extracting the snow cover rate through MODIS remote sensing data and collecting meteorological data. The results showed that the snowmelt runoff model could well simulate the runoff process of Kuitun River catchment , and its Nash efficiency coefficients in both calibration and validation perio dsexceeded 07, which means that the snowmelt runoff model can be applied to flood fo recasting in Kuitun River. The model has some guiding significance for the flood prevention and early warning in medium and small river catchments of high-cold mountainous areas.
The medium and small riv ers in China generally have low flood contro lstandards and urgent lyneed st rengthened flood forecasting , especially in high-cold mountaino us areas with insufficient stations and data, where it is difficult to disting uish the runoff produced by snowmelt from that by precipitation, which enhances the difficulty of flood for ecasting . Snowmelt Runoff Model ( SRM ) is a hydro logical model fo rsimulating and forecasting the snow melt runoff in mountainous watersheds. It plays an important role in the study of mountainous watersheds with snow melt and precipitation as the main runoff sources. Based on SRM and taking Kuitun River as a typical case of medium and small rivers in high-cold mountainous areas of Xinjiang , we simulated the daily runoff of the catchment by extracting the snow cover rate through MODIS remote sensing data and collecting meteorological data. The results showed that the snowmelt runoff model could well simulate the runoff process of Kuitun River catchment , and its Nash efficiency coefficients in both calibration and validation perio dsexceeded 07, which means that the snowmelt runoff model can be applied to flood fo recasting in Kuitun River. The model has some guiding significance for the flood prevention and early warning in medium and small river catchments of high-cold mountainous areas.
2018, 16(1):57-62.
Abstract:
Flood risk analysis is an important part of non-engineering flood cont rolmeasures, and flood hazard assessment is the basis of risk analysis. Due to the need to obtain submerged water depth, the existing assessment methods of flood hazard requires complex hydraulic models and high-resolution data, but during operation, it is often impossible to meet the data requirements. In order to simplify the process of flood hazard assessment and ensure the accuracy of the results, this paper presents a new simple and integ rated floo d hazard index . T he index is based o n Gisnet and Ar cGIS and combines w it h the distributed hy dr olog ical mo del. In light o f the fo rmation mechanism of flood hazard, the index comprehensively considers the natural attribute of distributed streamflow and topographic index. Based on the specific situation of the Hongluogu in Beijing mountain area, we tested the new index. The results showed that FHI can truly reflect the trend of regional flood with spatial change. It can provide a new idea for the future flood hazard assessment, and has great significance to the improvement of flood risk study system.
Flood risk analysis is an important part of non-engineering flood cont rolmeasures, and flood hazard assessment is the basis of risk analysis. Due to the need to obtain submerged water depth, the existing assessment methods of flood hazard requires complex hydraulic models and high-resolution data, but during operation, it is often impossible to meet the data requirements. In order to simplify the process of flood hazard assessment and ensure the accuracy of the results, this paper presents a new simple and integ rated floo d hazard index . T he index is based o n Gisnet and Ar cGIS and combines w it h the distributed hy dr olog ical mo del. In light o f the fo rmation mechanism of flood hazard, the index comprehensively considers the natural attribute of distributed streamflow and topographic index. Based on the specific situation of the Hongluogu in Beijing mountain area, we tested the new index. The results showed that FHI can truly reflect the trend of regional flood with spatial change. It can provide a new idea for the future flood hazard assessment, and has great significance to the improvement of flood risk study system.
2018, 16(1):63-68.
Abstract:
Based on the Copula theory, this study has constructed the joint distribution of SPEI between the water source area and the Hai River water receiving area in the middle route of the South-to-North Water Transfer Project in China ( SNWTP) at three time scales, i.e.the flooding season, the dryseason, and the whole year. Using the future climate model data, we computed the encounter probability of drought between the water source area and the Hai River water receiving area. The results showed that both the water source area and the water receiving area were undergoing a slight drying trend over the past few decades. Compared with the baseline, the probability of concurrent drought events will increase by different degrees in the RCP4.5 and RCP8.5 scenarios. Especially, the probability of concurrent drought during the flooding season and the probability of concurrent heavy drought during the dryseason increased obviously by 2. 99% ~ 6. 1% and 2. 67% ~ 3. 63% , respectively. The increase in the probability of concurrent drought between the water source area and water receiving area will probably influence the operation of SNWTP. Therefore, it's necessary to take some adaptive measures to ensure the safety and efficiency of SNWTP.
Based on the Copula theory, this study has constructed the joint distribution of SPEI between the water source area and the Hai River water receiving area in the middle route of the South-to-North Water Transfer Project in China ( SNWTP) at three time scales, i.e.the flooding season, the dryseason, and the whole year. Using the future climate model data, we computed the encounter probability of drought between the water source area and the Hai River water receiving area. The results showed that both the water source area and the water receiving area were undergoing a slight drying trend over the past few decades. Compared with the baseline, the probability of concurrent drought events will increase by different degrees in the RCP4.5 and RCP8.5 scenarios. Especially, the probability of concurrent drought during the flooding season and the probability of concurrent heavy drought during the dryseason increased obviously by 2. 99% ~ 6. 1% and 2. 67% ~ 3. 63% , respectively. The increase in the probability of concurrent drought between the water source area and water receiving area will probably influence the operation of SNWTP. Therefore, it's necessary to take some adaptive measures to ensure the safety and efficiency of SNWTP.
2018, 16(1):69-74.
Abstract:
The reaso nable parameter settings in the particle swarm optimization algorithm canimprove the optimization efficiency and avoidfalling into the local optimum. However, common parameter settings are not universally applicable to specific optimization problems, such as the simulation of Xin'anjiang model. In this study, we conducted orthogonal tests to study the influence of 5 particle swarm parameters on the simulat ionresults of Xin’anjiang model. Through the analysis of the test results, we revealed the influence of parameters on the performance of PSO algorithm and obtained the optimum parameters ( pop = 80, w = linear regression from 1.3 to 0.4, c? = 1. 85, c? = 2. 5, m= 0. 05) . Through range analysis and variance analysis, we found that the parameters pop and warehighly significant to the simulation results, and the other three parameters are not significant to the simulation results. The different PSO parameter sets were applied to Xin’anjiang model simulation, and proved that the reasonable PSO algorithm parameter setting can effectively improvet he simulation accuracy of Xin'anjiang model. Through the trend analysis of each factor, we obtained the relationship between the change trend of the factor value and the change trend of the model result. The method presented in this paper can providereference for finding the parameters of PSO algorithm in a specific application scenario.
The reaso nable parameter settings in the particle swarm optimization algorithm canimprove the optimization efficiency and avoidfalling into the local optimum. However, common parameter settings are not universally applicable to specific optimization problems, such as the simulation of Xin'anjiang model. In this study, we conducted orthogonal tests to study the influence of 5 particle swarm parameters on the simulat ionresults of Xin’anjiang model. Through the analysis of the test results, we revealed the influence of parameters on the performance of PSO algorithm and obtained the optimum parameters ( pop = 80, w = linear regression from 1.3 to 0.4, c? = 1. 85, c? = 2. 5, m= 0. 05) . Through range analysis and variance analysis, we found that the parameters pop and warehighly significant to the simulation results, and the other three parameters are not significant to the simulation results. The different PSO parameter sets were applied to Xin’anjiang model simulation, and proved that the reasonable PSO algorithm parameter setting can effectively improvet he simulation accuracy of Xin'anjiang model. Through the trend analysis of each factor, we obtained the relationship between the change trend of the factor value and the change trend of the model result. The method presented in this paper can providereference for finding the parameters of PSO algorithm in a specific application scenario.
2018, 16(1):75-82.
Abstract:
The terrest rial water storage( TWS) is an important indicator of regional water resources changes and water balance. The Gravity Recovery and Climate Experiment ( GRACE) offers the data fo r research of variation in large-scale TWS. In this paper, we used the data of GRACE RL05 and the in-situ dataset to discover the spatial and temporal variation of TWS and its causes during 2003-2015 in the Qaidam Basin. The results showed that the variation of TWS showed an upward trend, with an ascending velocity of about 0.26 mm permonth. The multi year average increment of TWS gradually declined from the south to the north, and it ranged bet ween 8.29-69. 38 mm. The rise of TWS was consistent with the ascending trend of precipitation in the study area. The method based on GRACE data to calculate TWS can provide animportant support for the assessment of TWS variation in data-scarce region in the northwest of China.
The terrest rial water storage( TWS) is an important indicator of regional water resources changes and water balance. The Gravity Recovery and Climate Experiment ( GRACE) offers the data fo r research of variation in large-scale TWS. In this paper, we used the data of GRACE RL05 and the in-situ dataset to discover the spatial and temporal variation of TWS and its causes during 2003-2015 in the Qaidam Basin. The results showed that the variation of TWS showed an upward trend, with an ascending velocity of about 0.26 mm permonth. The multi year average increment of TWS gradually declined from the south to the north, and it ranged bet ween 8.29-69. 38 mm. The rise of TWS was consistent with the ascending trend of precipitation in the study area. The method based on GRACE data to calculate TWS can provide animportant support for the assessment of TWS variation in data-scarce region in the northwest of China.
2018, 16(1):83-88.
Abstract:
We obtained the variation of water storage in Huang-Huai-Hai area from 2003 to 2014 by using the monthly gravity field dat a from GRACE satellite data. Then we compared it with the precipitation data in the same period to analyze its interannual and annual temporal and spatial variation characteristics. The results indicated that: temporally , the water storage in the Huang-Huai-Hai area decreased by 0.42 mm/month in 2003-2014, and that in Haihe and Huaihe river sub-basins decreased by 0.52 mm/ month and 0.28 mm/ month respectively. Within a year, the water storage was in surplus only in February,September and December, reaching the maximum in September to 9.86mm; the maximum water deficit occurred in June at 56.65 mm. Spatially, the water storage decreased from south to north. The water deficit in Haihe river basin was more serious than that in Huaihe river basin. But as the season changes, the water deficit was relieved from south to north, and switched to surplus in winter. The spatial variation of water storage was mainly affected by precipitation, and also affected by regional agricultural layout and crop irrigation. GRACE data can facilitate the study of water storage variation in the Huang-Huai-H ai area and can provide basis for the scientific management and planning of regional water resources.
We obtained the variation of water storage in Huang-Huai-Hai area from 2003 to 2014 by using the monthly gravity field dat a from GRACE satellite data. Then we compared it with the precipitation data in the same period to analyze its interannual and annual temporal and spatial variation characteristics. The results indicated that: temporally , the water storage in the Huang-Huai-Hai area decreased by 0.42 mm/month in 2003-2014, and that in Haihe and Huaihe river sub-basins decreased by 0.52 mm/ month and 0.28 mm/ month respectively. Within a year, the water storage was in surplus only in February,September and December, reaching the maximum in September to 9.86mm; the maximum water deficit occurred in June at 56.65 mm. Spatially, the water storage decreased from south to north. The water deficit in Haihe river basin was more serious than that in Huaihe river basin. But as the season changes, the water deficit was relieved from south to north, and switched to surplus in winter. The spatial variation of water storage was mainly affected by precipitation, and also affected by regional agricultural layout and crop irrigation. GRACE data can facilitate the study of water storage variation in the Huang-Huai-H ai area and can provide basis for the scientific management and planning of regional water resources.
2018, 16(1):89-94.
Abstract:
In order to investigate the change tendencies of the droughts and floods in the Yangtze River basin, we used the standardized precipitation evapotranspiration index on multiple time scales, based on the monthly precipitation and average temperature data from the 133 meteorological stations in the whole basin during 1970-2012. The results showed that the overall drought conditions in the Yangtze River basin were not serious, while the drought tendency was prominent. Compared to the upstream region, the middle and lower reaches of the Yangtze River basin had a more prominent drought tendency, especially on longer time scales. In addition, the analysis of typical extreme meteorological events showed that the standar dized precipitation evapotranspiration index could well reflect the floods and droughts in the Yangtze River basin on different time scales. This suggests that the index can be used to precisely evaluate the extents and distributions of the hydrological regimes in this basin.
In order to investigate the change tendencies of the droughts and floods in the Yangtze River basin, we used the standardized precipitation evapotranspiration index on multiple time scales, based on the monthly precipitation and average temperature data from the 133 meteorological stations in the whole basin during 1970-2012. The results showed that the overall drought conditions in the Yangtze River basin were not serious, while the drought tendency was prominent. Compared to the upstream region, the middle and lower reaches of the Yangtze River basin had a more prominent drought tendency, especially on longer time scales. In addition, the analysis of typical extreme meteorological events showed that the standar dized precipitation evapotranspiration index could well reflect the floods and droughts in the Yangtze River basin on different time scales. This suggests that the index can be used to precisely evaluate the extents and distributions of the hydrological regimes in this basin.
2018, 16(1):95-99.
Abstract:
The Middle Route of the South-to-North Water Transfer Project has been running safely and the water quality along the line was up to standard in the past two years. The total outflow from Taocha canal headwork is more than 6 billion m3. In order to optimize the real-time water regulation of the Middle Route Project, it is necessary to systematically summarize the water regulation scheme, water regulation plan, and the water regulation practices in the past two years. This paper introduces the water regulation scheme of the project, the annual transferable water volume of Danjiangkou Reservoir, the annual water regulation plan, as well as the water regulation practices of the project in the past two years. It analyzes the water regulation benefits, actual water transfer volume, and water transfer loss of the Middle Route Project. It also reviews the practices of and existing problems in water regulation of the Middle Route Project and proposes corresponding suggestions.
The Middle Route of the South-to-North Water Transfer Project has been running safely and the water quality along the line was up to standard in the past two years. The total outflow from Taocha canal headwork is more than 6 billion m3. In order to optimize the real-time water regulation of the Middle Route Project, it is necessary to systematically summarize the water regulation scheme, water regulation plan, and the water regulation practices in the past two years. This paper introduces the water regulation scheme of the project, the annual transferable water volume of Danjiangkou Reservoir, the annual water regulation plan, as well as the water regulation practices of the project in the past two years. It analyzes the water regulation benefits, actual water transfer volume, and water transfer loss of the Middle Route Project. It also reviews the practices of and existing problems in water regulation of the Middle Route Project and proposes corresponding suggestions.
2018, 16(1):100-107.
Abstract:
In order to clarify the water poverty status of Sichuan province, in this study we established an evaluation index system of water poverty in Sichuan Province, calculated the water poverty index of the 21 cities from 2006 to 2013 by using balanced weighting and water poverty index model, and analyzed the temporal and spatial pattern of the province and each city based on the geog raphic information system ( GIS) . The results showed that from 2008 to 2011, the comprehensive and balanced water poverty improvement situation in Sichuan province was hindered by the Wenchuan earthquake on May 12th, 2008. As the government actively advanced water conservancy reconstruction and targeted poverty relief through water conservancy, the water poverty situation improved from 2006 to 2013. The enhancement of water management capacity and the improvement of water environment played a key role in advancing water security . Furthermore, the 21 cities varied greatly in their capacity to handle water poverty and the gapwasg radually widening . Chengdu City and Ya'an City were infinitesimal water poverty areas; Panzhihua City, Guangyuan City, Aba Prefecture, Ganzi Prefecture, and Liangshan Prefecture were slight water poverty areas; Luzhou City, Mianyang City, Leshan City, Meishan City , and Yibin City were moderate water poverty areas; Zigong City , Deyang City, Nanchong City , Bazhong City, and Ziyang City were strong water poverty areas; Suining City, Neijiang City, Guang'an City , and Dazhou City were extreme water poverty areas. The government should make more efforts to enhance water poverty awareness, increase the efficiency of water use, optimize the allocation of water resources, improve the scientific guarantee rate, manage water resources strictly, adjust industrial structure and production mode, systematically control the water safety risk, improve its water management ability , increase fiscal investment, actively promote the reform of water right system, streng then poverty relief through water conservancy, and boost poverty alleviation.
In order to clarify the water poverty status of Sichuan province, in this study we established an evaluation index system of water poverty in Sichuan Province, calculated the water poverty index of the 21 cities from 2006 to 2013 by using balanced weighting and water poverty index model, and analyzed the temporal and spatial pattern of the province and each city based on the geog raphic information system ( GIS) . The results showed that from 2008 to 2011, the comprehensive and balanced water poverty improvement situation in Sichuan province was hindered by the Wenchuan earthquake on May 12th, 2008. As the government actively advanced water conservancy reconstruction and targeted poverty relief through water conservancy, the water poverty situation improved from 2006 to 2013. The enhancement of water management capacity and the improvement of water environment played a key role in advancing water security . Furthermore, the 21 cities varied greatly in their capacity to handle water poverty and the gapwasg radually widening . Chengdu City and Ya'an City were infinitesimal water poverty areas; Panzhihua City, Guangyuan City, Aba Prefecture, Ganzi Prefecture, and Liangshan Prefecture were slight water poverty areas; Luzhou City, Mianyang City, Leshan City, Meishan City , and Yibin City were moderate water poverty areas; Zigong City , Deyang City, Nanchong City , Bazhong City, and Ziyang City were strong water poverty areas; Suining City, Neijiang City, Guang'an City , and Dazhou City were extreme water poverty areas. The government should make more efforts to enhance water poverty awareness, increase the efficiency of water use, optimize the allocation of water resources, improve the scientific guarantee rate, manage water resources strictly, adjust industrial structure and production mode, systematically control the water safety risk, improve its water management ability , increase fiscal investment, actively promote the reform of water right system, streng then poverty relief through water conservancy, and boost poverty alleviation.
ZHANG Yuan
,
ZHAO Changsen
,
YANG Shengtian
,
LIU Changming
,
ZHANG Huitong
,
XIANG Hua
,
SUN Ying
,
YANG Zengli
,
HOU Zhiqiang
,
LIU Dehu
,
ZHANG Chunbin
,
YU Xinyi
2018, 16(1):108-113.
Abstract:
The study of ecological flow is a hot field in ecology and hydrology . However, the existing methodologies do not consider the functional integrity of an eco-system. In this study , we simulated the nutritional relationships between the communities of an eco-system in Xiao qinghe river basin using the model of Ecopath. After determining the key fishes, we analyzed the velo city and water level demand of the key fishes by the habitat suitable index. Finally,coupling the velo city and water level demand of multiple species, we calculated the eco-flow by the Adapted Ecological Hydraulic Radius Approach. The results showed that the water requirements of the upper, middle, and lower reaches were 4.28 m3/s, 0.74 m3/s, and 3.47 m3/s respectively in nonspawning season, and 23.52 m3/s, 5.96 m3/s ( or 8.65 m3/s) , 37.38 m3/s respectively in spawning season. Compared with the approach of Tennant, our method could keep the ecosystem’s health condition above the“average”level, and could satisfy the water requirement of the majority of aquatic organisms. Besides, this method shows the difference between spawning season and non-spawning season, thus gives reference for the seasonal regulation of water resources in the basin.
The study of ecological flow is a hot field in ecology and hydrology . However, the existing methodologies do not consider the functional integrity of an eco-system. In this study , we simulated the nutritional relationships between the communities of an eco-system in Xiao qinghe river basin using the model of Ecopath. After determining the key fishes, we analyzed the velo city and water level demand of the key fishes by the habitat suitable index. Finally,coupling the velo city and water level demand of multiple species, we calculated the eco-flow by the Adapted Ecological Hydraulic Radius Approach. The results showed that the water requirements of the upper, middle, and lower reaches were 4.28 m3/s, 0.74 m3/s, and 3.47 m3/s respectively in nonspawning season, and 23.52 m3/s, 5.96 m3/s ( or 8.65 m3/s) , 37.38 m3/s respectively in spawning season. Compared with the approach of Tennant, our method could keep the ecosystem’s health condition above the“average”level, and could satisfy the water requirement of the majority of aquatic organisms. Besides, this method shows the difference between spawning season and non-spawning season, thus gives reference for the seasonal regulation of water resources in the basin.
2018, 16(1):114-121.
Abstract:
In this paper, we investigated the overbank flood at the Huaxian section of the Wei River. First, we employed the top of bank (ToB) method to calculate the overbank flood level corresponding to different historical large profiles, and employed hydraulic methods to calculate the frequency, duration, and maximum flow of overbank floods at Huaxian section from 1965 to 2010. Moreover, with the frequency and duration of overbank floods as evaluation indexes, we used the range of variability approach ( RVA ) to evaluate the variation of the overbank flood time series and discussed its potential impact on the riparian ecosystems. The results showed that the overbank flood occurred 34 times at the Huaxian section of the Wei River in 1965-2010, that is 0.74 times a year. The frequency, duration, and maximum flow of overbank floods all showed a significant decreasing tendency over time. Especially since the 1990s, the over bank floods were mostly small floods due to flow reduction and sediment deposition in the lower reaches of the Wei River, and they had slower flow speed, smaller quantity, and limited ecological effects. Meanwhile, the evaluation results by RVA showed the frequency and duration of the overbank floods at Huaxian section both changed significantly , which would posegreat potential threat to the riparian environment. Thus, we suggest that the administration should take more measures such as artificial overbank floods to protect the ecological balance and security of riparian wetlands and beaches.
In this paper, we investigated the overbank flood at the Huaxian section of the Wei River. First, we employed the top of bank (ToB) method to calculate the overbank flood level corresponding to different historical large profiles, and employed hydraulic methods to calculate the frequency, duration, and maximum flow of overbank floods at Huaxian section from 1965 to 2010. Moreover, with the frequency and duration of overbank floods as evaluation indexes, we used the range of variability approach ( RVA ) to evaluate the variation of the overbank flood time series and discussed its potential impact on the riparian ecosystems. The results showed that the overbank flood occurred 34 times at the Huaxian section of the Wei River in 1965-2010, that is 0.74 times a year. The frequency, duration, and maximum flow of overbank floods all showed a significant decreasing tendency over time. Especially since the 1990s, the over bank floods were mostly small floods due to flow reduction and sediment deposition in the lower reaches of the Wei River, and they had slower flow speed, smaller quantity, and limited ecological effects. Meanwhile, the evaluation results by RVA showed the frequency and duration of the overbank floods at Huaxian section both changed significantly , which would posegreat potential threat to the riparian environment. Thus, we suggest that the administration should take more measures such as artificial overbank floods to protect the ecological balance and security of riparian wetlands and beaches.
2018, 16(1):122-126.
Abstract:
According to the previous research on Taihu Lake and other shallow lakes, the water movement is mainly affected by the direction of the wind. The form of the water movement is mainly the wind-driven flow . In order to study the basic characteristics of the wind-driven flow in shallow lakes, we established a flume experiment device to simulate the wind-driven flow at the 15 m/s wind speed. The PIV system with high sampling frequency was used to measure the precise hydrody namic characteristics of the wind-driven flow, and obtained the vertical flow field information of the wind-driven flow . The test showed that the measurement results of the system conformed to the formation law of wind-driven flow , and has the ability to simulate the wind-driven flow. By contrasting the vertical distribution of time-averaged flow field, horizontal velocity , vortex, turbulent shear stress, and turbulent intensity at different distances at the same wind speed, we analyzed the hydrodynamic charact eristics of the wind-driven flow. The results of this experiment can provide basic data for the further study on the hydrodynamic characteristics of shallow lakes.
According to the previous research on Taihu Lake and other shallow lakes, the water movement is mainly affected by the direction of the wind. The form of the water movement is mainly the wind-driven flow . In order to study the basic characteristics of the wind-driven flow in shallow lakes, we established a flume experiment device to simulate the wind-driven flow at the 15 m/s wind speed. The PIV system with high sampling frequency was used to measure the precise hydrody namic characteristics of the wind-driven flow, and obtained the vertical flow field information of the wind-driven flow . The test showed that the measurement results of the system conformed to the formation law of wind-driven flow , and has the ability to simulate the wind-driven flow. By contrasting the vertical distribution of time-averaged flow field, horizontal velocity , vortex, turbulent shear stress, and turbulent intensity at different distances at the same wind speed, we analyzed the hydrodynamic charact eristics of the wind-driven flow. The results of this experiment can provide basic data for the further study on the hydrodynamic characteristics of shallow lakes.
2018, 16(1):127-134.
Abstract:
To reveal the evolution mechanism of groundwater quality in Liulin karst system in northern China, we used the major ions and saturation indices to analyze the hydrochemical characteristics and geochemical processes. Meanwhile, we established a reverse geochemical model to quantitatively simulate the water-rock interactions in karst aquifers. The results showed that the hydrochemical type changed from HCO3-Ca· Mg in the recharge area to HCO3· SO4-Ca· Mg in the runoff area and to HCO3·SO4-Ca· Na in the discharge area. The geochemical processes of hydrochemical evolution in karst water were the dissolution of carbonate minerals and gypsum. Along the flow path, the processes were evolved from the simultaneous dissolution of calcite and dolomite in the recharge area to the dissolution of dolomite and gypsum in the runoff area, and the dissolution of halite was added in the discharge area. Besides, the dedolomitization and cation exchange between Na+ and Ca2+ in the runoff and discharge areas affected the hydrochemical types of karst groundwater in Liulin.
To reveal the evolution mechanism of groundwater quality in Liulin karst system in northern China, we used the major ions and saturation indices to analyze the hydrochemical characteristics and geochemical processes. Meanwhile, we established a reverse geochemical model to quantitatively simulate the water-rock interactions in karst aquifers. The results showed that the hydrochemical type changed from HCO3-Ca· Mg in the recharge area to HCO3· SO4-Ca· Mg in the runoff area and to HCO3·SO4-Ca· Na in the discharge area. The geochemical processes of hydrochemical evolution in karst water were the dissolution of carbonate minerals and gypsum. Along the flow path, the processes were evolved from the simultaneous dissolution of calcite and dolomite in the recharge area to the dissolution of dolomite and gypsum in the runoff area, and the dissolution of halite was added in the discharge area. Besides, the dedolomitization and cation exchange between Na+ and Ca2+ in the runoff and discharge areas affected the hydrochemical types of karst groundwater in Liulin.
2018, 16(1):135-143.
Abstract:
Spatial-temporal change of coverage is in favor of understanding the ecosystem response to climatic variability and human-induced land transformations. The objective of this study was to analysis veg etation dynamics its relationship with drought in Hutuo river basin, based on 250 m MODIS NDVI time-series data and monthly temperature and precipitation of 14 meteorological stations ( 2001-2015) . The characteristics of drought were studied using the drought index (standardized precipitation evapotranspiration index , SPEI) , and the monthly temperature and precipitation were used to compute the SPEI of 1, 3 and 12 month timescale. Results are show nas fo llows: (1) The NDVI of the study area was improvement progressively from 2001 to 2015, with a lineartendency being 0.024/(10a).(2) The largest proportion of the contribution to vegetation restoration was observed in the significantly improved area, and the area where the values of NDVI significantly increased accounts for reached 51.58% was mainly located in the upstream and midstream of Hutuo river basin. (3) The SPEI was fluctuating upward trend, which indicated that drought could be easing over the past 15 years in Hutuo river basin. And the trend was most marked in the midstream. (4) Correlation analysis results showed that the SPEI had a strong influence on vegetation coverage mainly occurred in June and July on the monthly , and temperature was the dominant factor affecting the change of vegetation in June, while precipitation was the dominant factor in July . Seasonally, drought in summer had more influence on vegetation coverage. There was a positive correlation between the annual NDVI and annual SPEI, and drought has a great influence on vegetation growth.
Spatial-temporal change of coverage is in favor of understanding the ecosystem response to climatic variability and human-induced land transformations. The objective of this study was to analysis veg etation dynamics its relationship with drought in Hutuo river basin, based on 250 m MODIS NDVI time-series data and monthly temperature and precipitation of 14 meteorological stations ( 2001-2015) . The characteristics of drought were studied using the drought index (standardized precipitation evapotranspiration index , SPEI) , and the monthly temperature and precipitation were used to compute the SPEI of 1, 3 and 12 month timescale. Results are show nas fo llows: (1) The NDVI of the study area was improvement progressively from 2001 to 2015, with a lineartendency being 0.024/(10a).(2) The largest proportion of the contribution to vegetation restoration was observed in the significantly improved area, and the area where the values of NDVI significantly increased accounts for reached 51.58% was mainly located in the upstream and midstream of Hutuo river basin. (3) The SPEI was fluctuating upward trend, which indicated that drought could be easing over the past 15 years in Hutuo river basin. And the trend was most marked in the midstream. (4) Correlation analysis results showed that the SPEI had a strong influence on vegetation coverage mainly occurred in June and July on the monthly , and temperature was the dominant factor affecting the change of vegetation in June, while precipitation was the dominant factor in July . Seasonally, drought in summer had more influence on vegetation coverage. There was a positive correlation between the annual NDVI and annual SPEI, and drought has a great influence on vegetation growth.
2018, 16(1):144-150.
Abstract:
The change of underlying surface and river system and its impact on hydrological process is one of the hot topics in hydrological studies especially in plain areas. In this study, we chose the Lixiahe district as the study area, and adopted RS and GIS technologies to study the changes in underlying surface and river system. The results showed that there was a significant change in land use during the urbanization of the study area. The proportion of urban area increased from 3.4% in 1980 to 2018% in 2014, while the area of paddy fields and water bo dy decreased1 The urban expansion evidently accelerated after 2000, and showed an eastw ard and southw ard tendency from the city center. Drainage density and water surface ratio both declined during the past 30 years. As a result , the structural complexity and the regional regulation and storage capacity of the river system also declined. The change of the river system was mainly charact erized by the reduction in low-grade rivers. Urbanization became the main driver in river system change after 2000. The degree of river system change had a significant linear relationship with urbanization in areas with an urbanization rate below 30% . The drainage density, water surface ratio, and box dimension were effective indicators of the quantitative and structural changes of the river system. The research results may enrich the case studies on river system change in plain areas, and provide basis for the funct ional planning and protection of the river system in this region in the future urbanization process.
The change of underlying surface and river system and its impact on hydrological process is one of the hot topics in hydrological studies especially in plain areas. In this study, we chose the Lixiahe district as the study area, and adopted RS and GIS technologies to study the changes in underlying surface and river system. The results showed that there was a significant change in land use during the urbanization of the study area. The proportion of urban area increased from 3.4% in 1980 to 2018% in 2014, while the area of paddy fields and water bo dy decreased1 The urban expansion evidently accelerated after 2000, and showed an eastw ard and southw ard tendency from the city center. Drainage density and water surface ratio both declined during the past 30 years. As a result , the structural complexity and the regional regulation and storage capacity of the river system also declined. The change of the river system was mainly charact erized by the reduction in low-grade rivers. Urbanization became the main driver in river system change after 2000. The degree of river system change had a significant linear relationship with urbanization in areas with an urbanization rate below 30% . The drainage density, water surface ratio, and box dimension were effective indicators of the quantitative and structural changes of the river system. The research results may enrich the case studies on river system change in plain areas, and provide basis for the funct ional planning and protection of the river system in this region in the future urbanization process.
2018, 16(1):151-157.
Abstract:
Rainstorm is a common weather phenomenon. It infuences the timely and sufficient water supply of long-distance canal system and engineering security. In this paper, we established a mathematical model to simulate the hydraulic responses under different rainstorm processes. The simulation results showed that: the rainstorm affects the operation security of the system, and the proper canal system operation can improve the security. Rainstorm can raise the water level, the extent of which depends on rainstorm intensity, rainstorm scope, and the location of the observed cross-section. The maximum increase occurs down the last canal pool. A 3-day rainstorm can increase the water level by 0.44m, endangering canal safety. With joint operation of the gates, the dammed water level can be effectively reduced, but it is still influenced by the contr ol mode of the canal system and par ameter values; and the risk position will be the first canal pool in the rainstorm-stricken area.
Rainstorm is a common weather phenomenon. It infuences the timely and sufficient water supply of long-distance canal system and engineering security. In this paper, we established a mathematical model to simulate the hydraulic responses under different rainstorm processes. The simulation results showed that: the rainstorm affects the operation security of the system, and the proper canal system operation can improve the security. Rainstorm can raise the water level, the extent of which depends on rainstorm intensity, rainstorm scope, and the location of the observed cross-section. The maximum increase occurs down the last canal pool. A 3-day rainstorm can increase the water level by 0.44m, endangering canal safety. With joint operation of the gates, the dammed water level can be effectively reduced, but it is still influenced by the contr ol mode of the canal system and par ameter values; and the risk position will be the first canal pool in the rainstorm-stricken area.
2018, 16(1):158-163.
Abstract:
In order to determine the reasonable channel roughness values for the Middle Route of South-to-North Water Diversion Project, we selected three methods ( Kai-lin Yang fo rmula, U.S. Bureau of Reclamation formula, and U.S. Army Corps of Engineers formula) and established one optimized method to caculate the roughness; then we tested the validity of the roughness values using the hydraulic model for main canal of South-to-North Water Diversion Project. The model and the method were applied to ten stable working conditions of the channel from Diaohe Gate to Tuanhe Gate. The roughness values caculated by the four methods were 0.01538, 0.0156, 0.01389, and 0.0169, respectively. Then the roughness values were put into the hydraulic model to caculate the water level behind Diao he Gate. The sum of relative error between caculated and measured values of the ten working conditions were 0.1744% , 0.1586% , 0.3028% , and 0.0947% , respectively . Results showed that the optimized method was the best at caculating channel roughness. We suggest that it be applied to South-to-North Water Diversion Project.
In order to determine the reasonable channel roughness values for the Middle Route of South-to-North Water Diversion Project, we selected three methods ( Kai-lin Yang fo rmula, U.S. Bureau of Reclamation formula, and U.S. Army Corps of Engineers formula) and established one optimized method to caculate the roughness; then we tested the validity of the roughness values using the hydraulic model for main canal of South-to-North Water Diversion Project. The model and the method were applied to ten stable working conditions of the channel from Diaohe Gate to Tuanhe Gate. The roughness values caculated by the four methods were 0.01538, 0.0156, 0.01389, and 0.0169, respectively. Then the roughness values were put into the hydraulic model to caculate the water level behind Diao he Gate. The sum of relative error between caculated and measured values of the ten working conditions were 0.1744% , 0.1586% , 0.3028% , and 0.0947% , respectively . Results showed that the optimized method was the best at caculating channel roughness. We suggest that it be applied to South-to-North Water Diversion Project.
2018, 16(1):164-169.
Abstract:
The piano-key weir is a new form of labyrinth weir and is characterized by a significant increase in the discharge capacity under the same weir width and water head condition. We used the RNG k-εtype turbulence mathematical model and the VOF method to deal with the free water surface and to establish a three-dimensional mathematical model. Through the calculation of the shape of the piano-key weir in different conditions, we obtained the flow regime, flow velocity , and other information of the three-dimensional flow field. The results were as follows. (1) The software Fluent was applicable to the numerical simulation of the piano-key weir, and it proved the remarkable discharge effect of the piano-key weir. (2) The three-dimensional flow field of the piano-key weir had a complex flow regime and the properties of ternary flow. The change of weir head would affect the discharge capacity of the piano-key weir. (3) The flow at the upper and lower reaches showed the state of open channel flow with a minimum velocity of 0.2 m/s. When the flow passed the weir, it formed water jets with increased velocity. There was air entering from the ventilation holes at the cavities between the water jets and the weir wall, forming a whirlpool. The air flow velocity was 2 m/s. After the water jets entered the water, there was air mixed with the water. The numerical simulation technique generated more detailed flow field information, which laid the foundation for further study of the flow field characteristics of the piano-key weir.
The piano-key weir is a new form of labyrinth weir and is characterized by a significant increase in the discharge capacity under the same weir width and water head condition. We used the RNG k-εtype turbulence mathematical model and the VOF method to deal with the free water surface and to establish a three-dimensional mathematical model. Through the calculation of the shape of the piano-key weir in different conditions, we obtained the flow regime, flow velocity , and other information of the three-dimensional flow field. The results were as follows. (1) The software Fluent was applicable to the numerical simulation of the piano-key weir, and it proved the remarkable discharge effect of the piano-key weir. (2) The three-dimensional flow field of the piano-key weir had a complex flow regime and the properties of ternary flow. The change of weir head would affect the discharge capacity of the piano-key weir. (3) The flow at the upper and lower reaches showed the state of open channel flow with a minimum velocity of 0.2 m/s. When the flow passed the weir, it formed water jets with increased velocity. There was air entering from the ventilation holes at the cavities between the water jets and the weir wall, forming a whirlpool. The air flow velocity was 2 m/s. After the water jets entered the water, there was air mixed with the water. The numerical simulation technique generated more detailed flow field information, which laid the foundation for further study of the flow field characteristics of the piano-key weir.
2018, 16(1):170-175.
Abstract:
Aiming at the change of pulsating pressure characteristics after aeration of water. Based on the test results of the rectangular chute hydraulic model, the variation laws of the standard deviation of pulsating pressure on the chute base-slab of different gas-absorbing facilities and different ventilation methods is analyzed. The results show that, in the condition of self aeration, the fluctuation pressure of the bottom plate is smooth along the curve; Forced aeration water flow pulsating pressure increased significantly, especially in the impacted area was a single peaklaw. Three kinds of aeration facilities: only set the bottom aerator, only set the lateral aerator and the bottom aerator and the lateral aerator set at the sametime, the effect of only set the lateral aeration on the pulsation of the bottom plate is the least. For the same bottom aerator, increasing the flow rate, increasing the vent area and decentralized vent holes will increaseing the pressure of the bottom chute.
Aiming at the change of pulsating pressure characteristics after aeration of water. Based on the test results of the rectangular chute hydraulic model, the variation laws of the standard deviation of pulsating pressure on the chute base-slab of different gas-absorbing facilities and different ventilation methods is analyzed. The results show that, in the condition of self aeration, the fluctuation pressure of the bottom plate is smooth along the curve; Forced aeration water flow pulsating pressure increased significantly, especially in the impacted area was a single peaklaw. Three kinds of aeration facilities: only set the bottom aerator, only set the lateral aerator and the bottom aerator and the lateral aerator set at the sametime, the effect of only set the lateral aeration on the pulsation of the bottom plate is the least. For the same bottom aerator, increasing the flow rate, increasing the vent area and decentralized vent holes will increaseing the pressure of the bottom chute.
2018, 16(1):176-188.
Abstract:
Flow-induced motion (FIM) is a typical fluid structure interaction (FSI) phenomenon, and is involved in aerodynamics, hydrodynamics, and ocean dynamics. Recently, as lots of FIM power convertors emerged, the study on FIM thrived again. Until now , there are lots of unsystematic directions in the research of FIM and its energy conversion. Thus, it is necessary to systematically analyze and discuss the situation and the problems in this research field. To this end, four parts are summarized and discussed in this study. First, the current situation of the study on the FIM for circular and non-circular cylinders is summarized. This paper points out that capturing the energy from FIM greatly benefits the utilization of current and wind energy. Then, it introduces the types, working principles, and applications of the main FIM power convertors in recent decades. Furthermore, based on the theories of FIM, it introduces and analyzes the current situation of FIM energy conversion research, and discusses the problems in the research. At last, some suggestions are proposed on the future study of FIM energy conversion.
Flow-induced motion (FIM) is a typical fluid structure interaction (FSI) phenomenon, and is involved in aerodynamics, hydrodynamics, and ocean dynamics. Recently, as lots of FIM power convertors emerged, the study on FIM thrived again. Until now , there are lots of unsystematic directions in the research of FIM and its energy conversion. Thus, it is necessary to systematically analyze and discuss the situation and the problems in this research field. To this end, four parts are summarized and discussed in this study. First, the current situation of the study on the FIM for circular and non-circular cylinders is summarized. This paper points out that capturing the energy from FIM greatly benefits the utilization of current and wind energy. Then, it introduces the types, working principles, and applications of the main FIM power convertors in recent decades. Furthermore, based on the theories of FIM, it introduces and analyzes the current situation of FIM energy conversion research, and discusses the problems in the research. At last, some suggestions are proposed on the future study of FIM energy conversion.
2018, 16(1):189-194.
Abstract:
Quantitative analysis on water resources value is of great significance to establishing a scientific and reasonable water price system and to alleviating the contradiction between supply and demand of water resources. We used the benef it sharing coefficient method to calculate the net benefit of industrial and agricultural unit water use in the intake area of the South-to-North Water Diversion Project（SNWDP) . Taking maximization of net benefit as the objectiv efunction, we established an optimal allocation model for water resources with water supply and demand as well as water diversion canal capacities as const raints. Linear programming method was applied in optimizing the model and calculating the shadow prices of local water resources in the subareas of the intake area of the SNWDP. For the intake area of the eastern route of the SNWDP, the shadow prices of water resources in the South of Yellow River, Shandong Peninsula, and North of Yellow River were 1.00 Yuan/m3 , 4.31 Yuan/m3 and 3.89 Yuan/m3 , respectively. For the intake area of the middle route of the SNWDP, the shadow prices of water resources in Henan, Hebei, Beijing , and Tianjin were 3.67 Yuan/m3, 4.41 Yuan/m3 , 2.20 Yuan/m3 and 2.19 Yuan/m3 , respectively . The results were the theoretical values of water resources, and could provide scientific support for establishing water price standards and improving water price system in the intake area of the SNWDP.
Quantitative analysis on water resources value is of great significance to establishing a scientific and reasonable water price system and to alleviating the contradiction between supply and demand of water resources. We used the benef it sharing coefficient method to calculate the net benefit of industrial and agricultural unit water use in the intake area of the South-to-North Water Diversion Project（SNWDP) . Taking maximization of net benefit as the objectiv efunction, we established an optimal allocation model for water resources with water supply and demand as well as water diversion canal capacities as const raints. Linear programming method was applied in optimizing the model and calculating the shadow prices of local water resources in the subareas of the intake area of the SNWDP. For the intake area of the eastern route of the SNWDP, the shadow prices of water resources in the South of Yellow River, Shandong Peninsula, and North of Yellow River were 1.00 Yuan/m3 , 4.31 Yuan/m3 and 3.89 Yuan/m3 , respectively. For the intake area of the middle route of the SNWDP, the shadow prices of water resources in Henan, Hebei, Beijing , and Tianjin were 3.67 Yuan/m3, 4.41 Yuan/m3 , 2.20 Yuan/m3 and 2.19 Yuan/m3 , respectively . The results were the theoretical values of water resources, and could provide scientific support for establishing water price standards and improving water price system in the intake area of the SNWDP.
2018, 16(1):195-202.
Abstract:
Located at the lower reaches of Jinsha River and middle reaches of Yangtze River, the cascadereservoirs system of Xi luodu, Xiangjia Dam, Three Gorges, and Gezhou Dam is an important hydrologic project in the Yangtze river basin. Joint operation of the reservoirs system has significant benefits. In this study , we established two optimized operation models for independent and joint power generation of the reservoirs system. Long inflow time series were used to calculate the gain of power generation benefit and to analyze the distribution of the gain in time, year type, and space. Moreover, we quantified the contribution percentages of released water and water head to the gain using the total differential equation. The results showed that: (1) the gain during the drawdown season mainly occurred in May, and was mostly in Gezhou Dam and Xiangjia Dam. (2) The gain was generated because Xiluodu and Three Gorges evened the water release process in May and June and reduced the discarded water volume of Xiangjia Dam and Gezhou Dam, thus increasing the water head of these two reservoirs. (3) The released water and water head contributed nearly equally to the gain generated in Xiangjia Dam. The main contribution factor to the gain in Gezhou Dam was water head. The variation of the gain generated in Xiluodu and Three Gorges was mainly influenced by the variation of water head during the joint operation.
Located at the lower reaches of Jinsha River and middle reaches of Yangtze River, the cascadereservoirs system of Xi luodu, Xiangjia Dam, Three Gorges, and Gezhou Dam is an important hydrologic project in the Yangtze river basin. Joint operation of the reservoirs system has significant benefits. In this study , we established two optimized operation models for independent and joint power generation of the reservoirs system. Long inflow time series were used to calculate the gain of power generation benefit and to analyze the distribution of the gain in time, year type, and space. Moreover, we quantified the contribution percentages of released water and water head to the gain using the total differential equation. The results showed that: (1) the gain during the drawdown season mainly occurred in May, and was mostly in Gezhou Dam and Xiangjia Dam. (2) The gain was generated because Xiluodu and Three Gorges evened the water release process in May and June and reduced the discarded water volume of Xiangjia Dam and Gezhou Dam, thus increasing the water head of these two reservoirs. (3) The released water and water head contributed nearly equally to the gain generated in Xiangjia Dam. The main contribution factor to the gain in Gezhou Dam was water head. The variation of the gain generated in Xiluodu and Three Gorges was mainly influenced by the variation of water head during the joint operation.
2018, 16(1):203-208.
Abstract:
Heavy rain is the direct cause of mountain torrents disasters. The early warning , forecast, and risk assessment of mountain torrents often involve the calculation of a series of heavy rain and flood elements. Because of the huge amount of data, the traditional method of calculating rainstorm and flood elements based on measured rainfall data is inefficient and difficult to implement. The commonly used calculation methods are mostly based on the basin area, net rainfall depth, and the length of confluence. They are simple and effective, but deliver poor accuracy. This paper puts forward a fast calculation method for rainstorm and flood in small basins, combining the traditional method and C# secondary development technology. This method guarantees calculation accuracy, and also greatly improves efficiency. The experimental results show that the new calculation method can generate the results more efficiently and accurately .
Heavy rain is the direct cause of mountain torrents disasters. The early warning , forecast, and risk assessment of mountain torrents often involve the calculation of a series of heavy rain and flood elements. Because of the huge amount of data, the traditional method of calculating rainstorm and flood elements based on measured rainfall data is inefficient and difficult to implement. The commonly used calculation methods are mostly based on the basin area, net rainfall depth, and the length of confluence. They are simple and effective, but deliver poor accuracy. This paper puts forward a fast calculation method for rainstorm and flood in small basins, combining the traditional method and C# secondary development technology. This method guarantees calculation accuracy, and also greatly improves efficiency. The experimental results show that the new calculation method can generate the results more efficiently and accurately .
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